To patients, such as diabetics, who have to frequently inject themselves with a drug, it is necessary to keep account of when an injection has to be made or when an injection last time took place. This information could be in the form either of exact time information, e.g. the next injection should take place at 5h00 or the last injection took place at 3h00, or the information may be provided as a dynamic timer or stop watch function, e.g. the next injection should take place in 3h45 or the last injection took place for 2h30.
A number of devices have been described which may provide a patient with useful information when using such devices for the injection of a drug such as insulin a number of times over the day.
EP 87 491 (Günter Petz) discloses a kit comprising a storage box for insulin vials and a syringe, the kit being provided with a timer device by which the time for the latest injection may be set manually. Further the hour for the next injection may be set and the timing device may function as an alarm clock sounding an alarm when it is time for this next injection. However, in a world where people in a short time may cross between different time zones, and the hours in the time zones even may shift from summer to winter time, a reference to the hour may be uncertain. Here the count down is more adequate but has the drawback that unless you are ready to take an injection immediately when the alarm sounds you will have a new time account to handle, e.g. for how long an interval was the alarm set and how long time has passed from the sound of the alarm till the injection is actually made. EP 87 491 is hereby incorporated by reference.
DE 38 24 217 (Pavel Han{hacek over (c)}l) discloses an injection device comprising timer and control means coupled to the injection actuation means, i.e. the exact time for each actuation of the device, and thus normally for an injection, is automatically captured by the timer and control means and stored in a memory. For each actuation (injection) performed the amount of drug infused is memorized together with a time stamp as in a log book, e.g. 5 units of a given insulin were infused at 4:38. The device is adapted for memorizing a number of such log book datasets which then can be recalled by the patient or any attendant medical staff person. The device may also be operated to indicate the time lapsed since the individual earlier injections took place. In addition to these features, DE 38 24 217 also discloses timer, stop watch and alarm means as known from EP 87 491. DE 38 24 217 is hereby incorporated by reference.
U.S. Pat. No. 6,248,090 (assigned to Novo Nordisk A/S) discloses an injection device having a dose setting mechanism, a button operable to carry out an injection movement to inject the set dose, a switch operated at the start or at the completion of the injection, or at a time between the start and the completion of the injection, the switch operating electronic timer means. In the disclosed embodiment the amount of the last dose is stored and a stop watch is reset and started when the switch is operated, the device comprising means for displaying to the user the time lapsed since the last reset, for example in pictogram form displaying one or more segments each representing a given amount of time. In this way, the stop watch counts the time passed (e.g. the number of full hours, each hour represented by a segment shown in a LCD display) from the latest operation of the switch, i.e. from the latest actuation (injection) performed, whereby the user may have a comprehensive view of the time which has passed after the latest injection and the size of this last injection. In this way the user is able to set the next dose with regard to these parameters. U.S. Pat. No. 6,248,090, is hereby incorporated by reference.
As appears from the above, devices have been described which provide the user with time information correlated to a specific injection action which has been performed by the user. In these devices the dose setting and injection mechanism are formed integrally with the electronic control, clock and display means necessary for providing the desired information, this resulting in a relatively expensive device most suited for use as a re-useable or durable device, e.g. a device which can be refilled with a drug such as a prefilled cartridge.
However, many users prefer to use prefilled, disposable injection devices such as the Flex Pen™ manufactured and sold by Novo Nordisk A/S. As such disposable devices have to be manufactured cost-effectively, the incorporation of electronic control and display means are normally dispensed with.
It would thus be desirable if users of disposable (or simple) devices could be provided with the same functionality as offered by more expensive (normally durable) devices, e.g. time indicator means providing information as to when the last actuation of a drug delivery device took place, which actuation normally would be associated with an injection performed by the user.